Electric machine

ABSTRACT

An electric machine is provided. The electric machine defines a centerline and includes: a stator assembly; a rotor assembly rotatable relative to the stator assembly about the centerline; and an actuator coupled to the rotor assembly, the stator assembly, or both for moving the rotor assembly, the stator assembly, or both along the centerline between a first position and a second position, the rotor assembly positioned closer to the stator assembly when in the first position than when in the second position.

FIELD

The present subject matter relates generally to an electric machinehaving one or more features enabling the electric machine to bemodulated from a fully enabled mode.

BACKGROUND

Typical aircraft propulsion systems include one or more gas turbineengines. For certain propulsion systems, the gas turbine enginesgenerally include a fan and a core arranged in flow communication withone another. Additionally, the core of the gas turbine engine generalincludes, in serial flow order, downstream of the fan, a compressorsection, a combustion section, a turbine section, and an exhaustsection. In operation, air is provided from the fan to an inlet of thecompressor section where one or more axial compressors progressivelycompress the air until it reaches the combustion section. Fuel is mixedwith the compressed air and burned within the combustion section toprovide combustion gases. The combustion gases are routed from thecombustion section to the turbine section. The flow of combustion gassesthrough the turbine section drives the turbine section and is thenrouted through the exhaust section, e.g., to atmosphere.

For certain aircraft propulsion systems, and aircraft incorporating suchaircraft propulsion systems, it may be beneficial for the propulsionsystem to include an electric machine to, e.g., generate electricalpower for various accessory systems of the gas turbine engines and/orthe aircraft, for electric or hybrid electric propulsion devices, etc.One issue with permanent magnet electric machines is that in the eventof a fault condition, such as a short within a stator coil, continuedrotation of the rotor continues to generate a magnetic flux/electricflow through such fault, potentially creating high temperatures. Whenthe electric machine is tied to an integral part of the aircraftpropulsion system, such as a primary gas turbine engine, it may not bepractical to shut down the gas turbine engine to prevent rotation of therotor of the electric machine.

Accordingly, a propulsion system for an aircraft having an electricmachine capable of addressing one or more of these issues would beuseful.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one embodiment of the present disclosure, an electric machine isprovided. The electric machine defines a centerline and includes: astator assembly; a rotor assembly rotatable relative to the statorassembly about the centerline; and an actuator coupled to the rotorassembly, the stator assembly, or both for moving the rotor assembly,the stator assembly, or both along the centerline between a firstposition and a second position, the rotor assembly positioned closer tothe stator assembly when in the first position than when in the secondposition.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a schematic, cross-sectional view of a gas turbine engine inaccordance with an exemplary aspect of the present disclosure.

FIG. 2 is a schematic, cross-sectional view of an electric machineembedded in a gas turbine engine in accordance with an exemplaryembodiment of the present disclosure in a first position.

FIG. 3 is a schematic, cross-sectional view of the exemplary electricmachine of FIG. 2 embedded in a gas turbine engine in a second position.

FIG. 4 is a schematic, cross-sectional view of a gas turbine engine inaccordance with another exemplary embodiment of the present disclosure.

FIG. 5 is a schematic, cross-sectional view of an electric machineembedded in a gas turbine engine in accordance with another exemplaryembodiment of the present disclosure in a first position.

FIG. 6 is a schematic, cross-sectional view of the exemplary electricmachine of FIG. 5 embedded in a gas turbine engine in a second position.

FIG. 7 is a flow diagram of a method for operating an electric machinein accordance with an exemplary aspect of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the invention.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

The terms “forward” and “aft” refer to relative positions within a gasturbine engine or vehicle, and refer to the normal operational attitudeof the gas turbine engine or vehicle. For example, with regard to a gasturbine engine, forward refers to a position closer to an engine inletand aft refers to a position closer to an engine nozzle or exhaust.

The terms “upstream” and “downstream” refer to the relative directionwith respect to fluid flow in a fluid pathway. For example, “upstream”refers to the direction from which the fluid flows, and “downstream”refers to the direction to which the fluid flows.

The terms “coupled,” “fixed,” “attached to,” and the like refer to bothdirect coupling, fixing, or attaching, as well as indirect coupling,fixing, or attaching through one or more intermediate components orfeatures, unless otherwise specified herein.

The singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

Approximating language, as used herein throughout the specification andclaims, is applied to modify any quantitative representation that couldpermissibly vary without resulting in a change in the basic function towhich it is related. Accordingly, a value modified by a term or terms,such as “about”, “approximately”, and “substantially”, are not to belimited to the precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value, or the precision of the methods or machines forconstructing or manufacturing the components and/or systems. Forexample, the approximating language may refer to being within a 10percent margin.

Here and throughout the specification and claims, range limitations arecombined and interchanged, such ranges are identified and include allthe sub-ranges contained therein unless context or language indicatesotherwise. For example, all ranges disclosed herein are inclusive of theendpoints, and the endpoints are independently combinable with eachother.

Referring now to the drawings, wherein identical numerals indicate thesame elements throughout the figures, FIG. 1 is a schematiccross-sectional view of a propulsion engine in accordance with anexemplary embodiment of the present disclosure. In certain exemplaryembodiments, the propulsion engine may be configured a high-bypassturbofan jet engine 100, herein referred to as “turbofan 100.” Theturbofan 100 may be incorporated into an aircraft propulsion system,e.g., as an under-wing mounted turbofan engine. Alternatively, however,in other embodiments, the turbofan 100 may be incorporated into anyother suitable aircraft or propulsion system.

As shown in FIG. 1 , the exemplary turbofan 100 depicted defines anaxial direction A (extending parallel to a longitudinal centerline 101provided for reference), a radial direction R, and a circumferentialdirection C (extending about the axial direction A; not depicted in FIG.1 ). In general, the turbofan 100 includes a fan section 102 and a coreturbine engine 104 disposed downstream from the fan section 102.

The exemplary core turbine engine 104 depicted generally includes asubstantially tubular outer casing 106 that defines an annular inlet108. The outer casing 106 encases, in serial flow relationship, acompressor section including a booster or low pressure (LP) compressor110 and a high pressure (HP) compressor 112; a combustion section 114; aturbine section including a high pressure (HP) turbine 116 and a lowpressure (LP) turbine 118; and a jet exhaust nozzle section 120. Thecompressor section, combustion section 114, and turbine section togetherdefine a core air flowpath 121 extending from the annular inlet 108through the LP compressor 110, HP compressor 112, combustion section114, HP turbine section 116, LP turbine section 118 and jet nozzleexhaust section 120. A high pressure (HP) shaft or spool 122 drivinglyconnects the HP turbine 116 to the HP compressor 112. A low pressure(LP) shaft or spool 124 drivingly connects the LP turbine 118 to the LPcompressor 110.

For the embodiment depicted, the fan section 102 includes a variablepitch fan 126 having a plurality of fan blades 128 coupled to a disk 130in a spaced apart manner. As depicted, the fan blades 128 extendoutwardly from disk 130 generally along the radial direction R. Each fanblade 128 is rotatable relative to the disk 130 about a pitch axis P byvirtue of the fan blades 128 being operatively coupled to a suitableactuation member 132 configured to collectively vary the pitch of thefan blades 128 in unison. The fan blades 128, disk 130, and actuationmember 132 are together rotatable about the longitudinal axis 101 by LPshaft 124 across a power gear box 134. The power gear box 134 includes aplurality of gears for stepping down the rotational speed of the LPshaft 124 to a more efficient rotational fan speed.

Referring still to the exemplary embodiment of FIG. 1 , the disk 130 iscovered by rotatable front hub 136 aerodynamically contoured to promotean airflow through the plurality of fan blades 128. Additionally, theexemplary fan section 102 includes an annular fan casing or outernacelle 138 that circumferentially surrounds the fan 126 and/or at leasta portion of the core turbine engine 104. The nacelle 138 is supportedrelative to the core turbine engine 104 by a plurality ofcircumferentially-spaced outlet guide vanes 140. A downstream section142 of the nacelle 138 extends over an outer portion of the core turbineengine 104 so as to define a bypass airflow passage 144 therebetween.

Additionally, the exemplary turbofan 100 depicted includes an electricmachine 146 rotatable with one or more rotatable components of theturbofan 100. Specifically, for the embodiment shown, the turbofan 100is rotatable with the low pressure system of the turbofan 100, includingthe LPshaft 124. Specifically, for the embodiment depicted, the electricmachine 146 is arranged co-axially with and mounted to the LP shaft 124(the LP shaft 124 also rotating the fan 126 through, for the embodimentdepicted, the power gearbox 134). As used herein, “co-axially” refers tothe axes being aligned. It should be appreciated, however, that in otherembodiments, an axis of the electric machine 146 may be offset radiallyfrom the axis of the LP shaft 124 and further may be oblique to the axisof the LP shaft 124, such that the electric machine 146 may bepositioned at any suitable location at least partially inward of thecore air flowpath 121.

The electric machine 146 includes a rotor assembly 148 and a statorassembly 150. For the embodiment depicted, the rotor assembly 148 andstator assembly 150 define a tapered air gap (see FIG. 2 ) and the rotorassembly 148 is configured to move relative to the stator assembly 150during certain operations, as will be explained in more detail below.

It should be also appreciated, however, that the exemplary turbofanengine 100 depicted in FIG. 1 is provided by way of example only, andthat in other exemplary embodiments, the turbofan engine 100 may haveany other suitable configuration. For example, in other exemplaryembodiments, the turbofan engine 100 may be configured as a turbopropengine, a turbojet engine, a differently configured turbofan engine, orany other suitable gas turbine engine. Additionally, or alternatively,exemplary aspects of the present disclosure (such as the electricmachine 146) may be incorporated into or otherwise utilized with anyother suitable type of engine, such as an aeroderivative gas turbineengine, a nautical gas turbine engine, a power generation gas turbineengine, an internal combustion engine, etc., or further with any othermachine having rotating components.

Referring now to FIG. 2 , an electric machine 146 embedded within a gasturbine engine in accordance with an exemplary embodiment of the presentdisclosure is depicted. In certain exemplary embodiments, the electricmachine 146 and gas turbine engine depicted in FIG. 2 may be configuredin substantially the same manner as the exemplary electric machine 146and turbofan engine 100 described above with reference to FIG. 1 .Accordingly, the same or similar numbers may refer to the same orsimilar parts.

As such, for the embodiment depicted, the electric machine 146 isembedded within a turbine section of the gas turbine engine, and moreparticularly still, is attached to an LP shaft 124 of the gas turbineengine. Additionally, the electric machine 146 is positioned at leastpartially within or aft of an LP turbine 118 of the turbine sectionalong an axial direction A.

It will be appreciated, however, that in other exemplary embodiments, aswill be explained more fully below, the electric machine 146 may bepositioned at other suitable locations within the gas turbine engine.

Referring to FIG. 2 , the electric machine 146 generally includes arotor assembly 148 and a stator assembly 150 and defines a centerline155, which for the embodiment depicted is aligned with a longitudinalaxis 101 of the engine. The rotor assembly 148 generally includes arotor connection member 152 and a rotor 154. The stator assembly 150similarly includes stator connection member 156 and a stator 158. Therotor 154 of the rotor assembly 148 and stator 158 of the statorassembly 150 together define an air gap 160 therebetween. In theembodiment shown, the rotor 154 includes a plurality of magnets 162,such as a plurality of permanent magnets, and the stator 158 includes aplurality of windings or coils 164. As such, it will be appreciated,that the electric machine 146 may be referred to as a permanent magnetelectric machine. However, in other exemplary embodiments, the electricmachine 146 may be configured in any suitable manner. For example, theelectric machine 146 may be configured as an electromagnetic electricmachine, including a plurality of electromagnets and active circuitry,as an induction type electric machine, a switched reluctance typeelectric machine, a synchronous AC electric machine, an asynchronouselectric machine, or as any other suitable electric generator or motor.

For the embodiment shown, the rotor assembly 148 is attached to the LPshaft 124, such that the rotor assembly 148 is rotatable with the LPshaft 124. The attachment of the rotor assembly 148 to the LP shaft 124will be described in more detail, below.

By contrast, the stator assembly 150 is attached to a structural supportassembly 166 of the turbine section. More specifically, the statorconnection member 156 extends from the structural support assembly 166to the stator 158 to support the stator 158. Notably, the structuralsupport assembly 166 is configured as part of an aft frame assembly 168,the aft frame assembly further including an aft frame strut 170extending through a core air flowpath 121 of the gas turbine engine andconfigured to provide structural support for the gas turbine engine. Thestructural support assembly 166 extends from an inner end of the aftframe strut 170 along the radial direction.

The gas turbine engine further includes a cavity wall 172 surrounding atleast a portion of the electric machine 146. More specifically, for theembodiment depicted, the cavity wall 172 substantially completelysurrounds the electric machine 146, extending from a location proximatea forward end of the electric machine 146 to a location aft of theelectric machine 146. The cavity wall 172 may function as, e.g., acooling air cavity wall, a sump for cooling fluid, a protective coverfor the electric machine 146, etc. For example, in certain embodiments,the engine may further include a second cavity wall (not shown) to forma buffer cavity surrounding the electric machine 146 and thermallyprotect the electric machine 146.

Referring still to the embodiment of FIG. 2 , during certain operationsof the gas turbine engine, the LP shaft 124 may rotate the rotorassembly 148 of the electric machine 146, allowing electric machine 146to function as an electric generator producing electrical power.Additionally, the electric machine 146 is in electrical communicationwith—electrically connected to—the electric communication bus 174. Theelectric communication bus 174 is electrically connected to the electricmachine 146 at a location inward of the core air flowpath 121 along theradial direction R. The electric communication bus 174 may extendthrough the core air flowpath 121 (e.g., through the aft frame strut170) and connect the electric machine 146 to various other electricalsinks (accessory systems, electric/hybrid-electric propulsion devices,etc.), electrical sources (other electric machines, electric energystorage units, etc.), or both. In such a manner, it will be appreciatedthat the electric machine 146 may further be operable as an electricmotor during certain operations, such that the rotor assembly 148 of theelectric machine 146 drives the LP shaft 124.

Referring now also to FIG. 3 , providing another view of the exemplaryelectric machine 146 FIG. 2 , it will be appreciated that electricmachine 146 is movable between a first position and a second position,or more specifically, the rotor assembly 148 is movable relative to thestator assembly 150 between the first position, as is shown in FIG. 2 ,and a second position, as is shown in FIG. 3 . More particularly, forthe embodiment shown, the electric machine 146 further includes anactuator 176 coupled to the rotor assembly 148, the stator assembly 150,or both for moving one of the rotor assembly 148 or stator assembly 150relative to the other of the rotor assembly 148 or stator assembly 150along the centerline 155 of the electric machine 146 between the firstposition and the second position. More specifically for the embodimentshown, as described in more detail below, the actuator 176 is coupled tothe rotor assembly 148 for moving the rotor assembly 148 relative to thestator assembly 150 along the centerline 155 of the electric machine 146between the first position and the second position. As depicted, therotor assembly 148 is positioned closer to the stator assembly 150 whenin the first position than when in the second position. The first andsecond positions are explained in more detail below.

More particularly, as noted above, the rotor assembly 148 is coupled tothe LP shaft 124 for the embodiment shown. More specifically, the rotorassembly 148 includes the rotor 154 and the rotor connection member 152.The rotor connection member 152 extends between the LP shaft 124 and therotor 154 for connecting the rotor 154 to the LP shaft 124. For theembodiment shown, the rotor connection member 152 is connected to the LPshaft 124 through a splined connection. More particularly, the rotorconnection member 152 includes a connection portion 178 having aplurality of teeth 180 extending generally along the axial direction A,and similarly, the LP shaft 124 includes a connection portion 182 havinga plurality of teeth 184 extending generally along the axial directionA. The plurality of teeth 180 of the connection portion 178 of the rotorconnection member 152 are configured to engage with the plurality ofteeth 184 of the connection portion 182 of the LP shaft 124, fixing thetwo components to one another along a circumferential direction C.Notably, however, such a configuration allows for relative movement ofthe rotor assembly 148 relative to the LP shaft 124 along the axialdirection A.

It will be appreciated, however, that in other embodiments, the rotorconnection member 152 may be coupled to the LP shaft 124 in any othersuitable manner allowing for relatively movement along the axialdirection, while fixing the components along the circumferentialdirection C. For example, in other example embodiments, the rotorconnection member 152 may be coupled to the LP shaft 124 using aplurality of linear bearings, linear slides, etc.

Moreover, it will further be appreciated that the actuator 176 iscoupled to the rotor connection member 152 of the rotor assembly 148 formoving the rotor connection member 152 along the centerline 155 of theelectric machine 146 relative to the LP shaft 124. In such a manner, theactuator 176 may move the rotor assembly 148 along the axial directionA, and along the centerline 155 of the electric machine 146, relative tothe LP shaft 124.

Briefly, for the embodiment shown, the actuator 176 is a linear actuator176, generally include a base 186 and an extension portion 188 moveablerelative to the base 186 along the axial direction A. The extensionportion 188 is rotatably coupled to the rotor connection member 152,supported by a plurality of bearings 190 (which for the embodimentdepicted include an axial-load bearing, or rather a ball bearing). Insuch a manner, it will be appreciated that the rotor connection member152 may rotate relative to the extension portion 188 along thecircumferential direction C, but is fixed to the extension portion 188along the axial direction A.

Further, it will be appreciated that the actuator 176 may be ahydraulically powered actuator, a pneumatically powered actuator, anelectrically powered actuator, a thermally activated actuator, amagnetic actuator, etc. Further, still, in other embodiments, theactuator 176 may not be a linear actuator, and instead may be ascissor-actuator, a circular to linear actuator (such as a screwactuator), or any other actuator capable of creating a linear movement.

Referring still to the embodiment of FIG. 2 , for the embodimentdepicted it will be appreciated that the actuator 176 is further coupledto the structural support assembly 166 of the turbine section, which asnoted above, is part of an aft frame assembly 168 having the aft framestrut 170. In such manner, it will be appreciated that the actuator 176is coupled to the same frame as the stator assembly 150. Notably, such aconfiguration may ensure the air gap 160 defined between the rotor 154of the rotor assembly 148 and the stator 158 of the stator assembly 150is maintained at a desired value during operation of the gas turbineengine having the electric machine 146 described herein. Morespecifically, as will be appreciated, as the gas turbine engine changesoperating conditions, a temperature of various components may increaseor decrease. For example, the LP shaft 124 may increase in temperature,which may cause the LP shaft 124 to increase in length along the axialdirection A. The connection of the actuator 176 to the same frame as thestator assembly 150, along with the splined connection between the rotorconnection member 152 and the LP shaft 124, may ensure that any increaseor decrease in length of the LP shaft 124 does not appreciably affect asize of the air gap 160 defined between the rotor 154 of the rotorassembly 148 and the stator 158 of the stator assembly 150.

Referring still to FIGS. 2 and 3 , it will be appreciated that for theembodiment shown, the first position is an engaged position and thesecond position is a disengaged position. As used herein, the term“engaged position” refers to a relative positioning of the rotor 154 ofthe rotor assembly 148 to the stator 158 of the stator assembly 150 inwhich the electric machine 146 is capable of operating within areasonable margin of error of the design efficiency for the electricmachine 146. For example, in the engaged position, the air gap 160defined between the rotor 154 of the rotor assembly 148 and the stator158 of the stator assembly 150 may be within a reasonable margin of anoptimal design value, enabling a desired portion of magnetic flux fromthe magnets 162 of the rotor 154 to reach the stator 158. By contrast,as used herein, the term “disengaged position” refers to a relativepositioning of the rotor 154 of the rotor assembly 148 to the stator 158of the stator assembly 150 in which the electric machine 146 is notcapable of operating with a reasonable efficiency (e.g., with anefficiency less than 10% of a maximum efficiency).

Moreover, for the embodiment shown, it will be appreciated that theelectric machine 146 is integrated into an interior position of the gasturbine engine (inward of a core air flowpath 121), wherein there maynot be an excess amount of space. Accordingly, in order to facilitatethe movement of the rotor assembly 148 relative to the stator assembly150 between the engaged position and the disengaged position, the airgap 160 defines an angle 192 relative to the centerline 155 of theelectric machine 146 greater than 0 degrees and less than 90. Morespecifically, for the embodiment shown, the angle 192 defined by the airgap 160 relative to the centerline 155 of the electric machine 146 isgreater than 10 degrees in less than 45 degrees, such as less than 30degrees. Such a configuration may facilitate movement between theengaged position and the disengaged position without requiring an excessamount of movement of the rotor assembly 148 relative to the statorassembly 150 along the centerline 155 of the electric machine 146.

For example, for the embodiment shown, a size of the air gap 160 (adistance 194, shown in FIG. 3 ) may be a first value when the rotorassembly 148 is in the engaged position relative to the stator assembly150, and may be equal to a second value when the rotor assembly 148 isin the disengaged position relative to the stator assembly 150. In atleast certain exemplary embodiments, the second value is at least twotimes larger than the first value, such as at least four times largerthan the first value, such as at least five times larger than the firstvalue, such as up to 200 times larger than the first value, such as upto 100 times larger than the first value, such as up to 20 times largerthan the first value.

Further, given the angle 192 the air gap 160 defines the centerline 155,such may be achieved with relatively small movements along thecenterline 155. For example, in embodiments, the actuator 176 may beconfigured to move the rotor 154 simply a distance along the centerline155 relative to the stator assembly 150 between the engaged position andthe disengaged position, with the distance being greater than 0.5 inchesand less than 10 inches, such as greater than 1 inch and less than 5inches.

An electric machine 146 configured in accordance with one or more theseexemplary embodiments may provide for an extra layer of safety in theevent of a failure of the electric machine 146. More specifically, aswill be appreciated, in the event of a short or other fault within thestator 158 of the stator assembly 150 (e.g., within a winding or coil164), continued rotation of the rotor 154 of the rotor assembly 148relative to the stator 158, when the rotor assembly 148 is in theengaged position relative to the stator assembly 150, may create excessheat, potentially damaging other components within the gas turbineengine. By utilizing an actuator 176 to move the rotor assembly 148 fromthe engaged position to the disengaged position, the gas turbine enginemay continue to operate without risking such additional damage to thegas turbine engine. Such may be particularly useful when the gas turbineengine is, e.g., an aeronautical gas turbine engine crating thrust foran aircraft.

In such a manner, briefly it will be appreciated that the exemplaryelectric machine 146 depicted further includes one or more sensors 196and a controller 198 operable with the actuator 176 and the one or moresensors 196. The controller 198 may be configured to receive data fromthe one or more sensors 196 which may be indicative of a fault withinthe electric machine 146. For example, the one or more sensors 196 maybe, e.g., one or more temperature sensors 196 configured to sense dataindicative of a temperature of the stator 158 of the stator assembly150. If the data sensed by the one or more sensors 196 indicates that atemperature of the stator 158 of the stator assembly 150 is in excess ofa certain threshold, such may be indicative of a fault within theelectric machine 146. The controller 198 may actuate the actuator 176 tomove the rotor assembly 148 from the first position, or rather theengaged position, to the second position, or rather the disengagedposition, in response to receiving data from the one more sensors 196indicative of the fault within the electric machine 146.

It will be appreciated that although the controller 198 is depicted at alocation proximate to the electric machine 146, in other embodiments,the controller 198 may be located at any suitable position within thegas turbine engine, or elsewhere (e.g., within an aircraft including theengine, at a remote location, etc.); may be a stand-alone controller, ormay be integrated into an existing controller for the engine (e.g., aFADEC); etc.

In such a manner, the controller 198 may prevent a fault within theelectric machine 146 from damaging other components of the gas turbineengine.

In addition to the above functionality, it should be appreciated thatthe actuator 176 may be configured to additionally move the rotorassembly 148 along the centerline 155 to one or more of a partial powerpositions located between the first position and the second position, orrather between the engaged position and the disengaged position. In suchmanner, the actuator 176 may be configured to move the rotor assembly148 relative to stator assembly 150 in order to affect an efficiency ofthe electric machine 146, to effectively control an amount of powerextracted by the electric machine 146 (or provided to the engine). Insuch manner, it will be appreciated that the controller 198 may furtherbe configured to move the rotor assembly 148 relative to the statorassembly 150 to control an amount of power extraction from the electricmachine 146.

It will further be appreciated that the exemplary electric machine 146and gas turbine engine depicted in FIGS. 2 and 3 is provided by way ofexample only. In other exemplary embodiments, the electric machine 146and gas turbine engine may have any other suitable configuration. Forexample, in other exemplary embodiments, the electric machine may bepositioned in any other suitable location within the gas turbine engine.For example, referring briefly to FIG. 4 , a gas turbine engine (orrather turbofan 100) configured in a manner similar to exemplary gasturbine engine of FIG. 1 is provided. As indicated by the phantom lines,it will be appreciated that the exemplary gas turbine engine may includean electric machine 146 at various other suitable locations. Forexample, the gas turbine engine may include a first electric machine146A coupled to the LP shaft 124 at a location forward of an LPcompressor 110. Additionally, or alternatively, the gas turbine enginemay include a second electric machine 146B coupled to the LP shaft 124,and HP shaft, or both within the compressor section at a locationforward of the HP compressor 112. Additionally, or alternatively, still,the gas turbine engine may include a third electric machine 146C coupledto the LP shaft 124, the HP shaft, or both within the compressor sectionat a location inward of the HP compressor 112. Additionally,alternatively, still, the gas turbine engine may include a fourthelectric machine 146D coupled with the LP shaft 124 within the turbinesection, at a location forward of the LP turbine 118.

Moreover, in still other embodiments, a gas turbine engine may beprovided having an electric machine 146 in accordance with one or moreexemplary embodiments of the present disclosure at still other suitablelocation. For example, referring now to FIGS. 5 and 6 , close-up,schematic, cross-sectional views are provided of an LP compressor 110,or booster compressor, of a gas turbine engine having an electricmachine 146 in accordance with an exemplary embodiment of the presentdisclosure. FIG. 5 provides a view of the exemplary electric machine 146in a first position, and FIG. 6 provides a view of the exemplaryelectric machine 146 in a second position.

The LP compressor 110 of the gas turbine engine depicted generallyincludes a plurality of LP compressor rotor blades 200 and a pluralityof LP compressor stator vanes 202. The plurality of LP compressor rotorblades 200 includes a plurality of stages 204 of LP compressor rotorblades 200 spaced along an axial direction A of the gas turbine engine.The gas turbine engine further includes a frame assembly 206, which maybe a compressor forward frame. For the embodiment shown the certain ofthe LP compressor stator vanes 202 are coupled to the frame assembly206.

Further, as noted above, the exemplary gas turbine engine includes anelectric machine 146 configured in accordance with an exemplaryembodiment of the present disclosure. In such manner, will beappreciated that the exemplary electric machine 146 generally includes astator assembly 150 and a rotor assembly 148 rotatable about acenterline 155 (not depicted in FIGS. 5 and 6 ; the centerline 155aligned with an engine centerline) relative to the stator assembly 150.The rotor assembly 148 includes a rotor 154 and the stator assembly 150includes a stator 158, with the rotor 154 and the stator 158 defining anair gap 160 therebetween.

Moreover, the exemplary electric machine 146 includes an actuator 176coupled to the rotor assembly 148, the stator assembly 150, or both formoving the rotor assembly 148 or the stator assembly 150 relative to theother of the rotor assembly 148 or the stator assembly 150 along thecenterline 155 between the first position and a second position.

However, for the exemplary embodiment of FIGS. 5 and 6 , the actuator176 is more specifically coupled to the stator assembly 150 for movingthe stator assembly 150 relative to the rotor assembly 148 along thecenterline 155 between the first position and a second position. As withthe embodiment above, the first position is an engaged position, asdepicted in FIG. 5 , and the second position is a disengaged position,as is depicted in FIG. 6 . As will be appreciated, the rotor assembly148 is positioned closer to the stator assembly 150 when in the engagedposition as compared to when in the disengaged position.

Further for the exemplary embodiment of FIGS. 5 and 6 , the rotorassembly 148 is not coupled to an LP shaft 124 of the engine, andinstead is coupled to a plurality of rotor blades of the gas turbineengine at a location outward of the plurality rotor blades of the gasturbine engine along a radial direction R of the gas turbine engine.More specifically, for the embodiment depicted, the plurality of rotorblades is a plurality of LP compressor rotor blades 200 in a stage 204of LP compressor blades 200.

It will be appreciated that in still other exemplary embodiments, thegas turbine engine, electric machine 146, or both may have still othersuitable configurations. Further, although the exemplary electricmachine 146 described herein is depicted within and described with a gasturbine engine, in other exemplary embodiments, the exemplary electricmachine 146 may be utilized with any other suitable machine having atleast one rotating component (motor or otherwise; aeronautical orotherwise; etc.).

Referring now to FIG. 7 , a flow diagram of a method 300 of operating anelectric machine in accordance with an exemplary aspect of the presentdisclosure is depicted. In certain exemplary aspects, the method mayutilize one or more of the exemplary electric machines described abovewith reference to FIGS. 1 through 6 . Accordingly, in certain exemplaryaspects the electric machine may include a stator assembly and a rotorassembly, and may define a centerline.

As is depicted, the method 300 includes at (302) operating the electricmachine to convert electrical power to rotational power, to convertrotational power to electrical power, or both while the rotor assemblyis in a first position relative to the stator assembly. For example,operating the electric machine at (302) may include operating theelectric machine to convert rotational power of an engine (such as anaeronautical gas turbine engine) to electrical power during a flightoperation, such as a takeoff operation, a climb operation, a cruiseoperation, and/or a descent operation, or alternatively during a groundoperation.

Further, for the aspect depicted, the method 300 includes at (304)receiving information indicative of a fault condition within theelectric machine. Receiving information indicative of the faultcondition within the electric machine at (304) may include receivinginformation indicative of a short within a stator winding or coil of thestator assembly. For example, receiving information indicative of thefault condition within the electric machine at (304) may includereceiving information indicative of a temperature of one or more aspectsof the stator assembly.

As is also depicted in FIG. 7 , the method 300 further includes at (306)moving one of the rotor assembly or stator assembly relative to theother of the rotor assembly or stator assembly along the centerline ofthe electric machine from the first position to a second position inresponse to receiving information indicative of the fault conditionwithin the electric machine, the rotor assembly positioned closer to thestator assembly in the first position than in the second position.

In at least certain exemplary aspects, such as the exemplary aspect ofFIG. 7 , moving one of the rotor assembly or stator assembly relative tothe other of the rotor assembly or stator assembly along the centerlineof the electric machine from the first position to a second position at(306) includes at (308) moving the rotor assembly relative to the statorassembly along the centerline of the electric machine from the firstposition to the second position with an actuator coupled to the rotorassembly.

Further for the exemplary aspect of FIG. 7 , it will be appreciated thatthe rotor assembly and stator assembly together define an air gaptherebetween. The air gap defines an angle relative to the centerlinegreater than zero degrees and less than 90 degrees. With such anexemplary aspect, moving one of the rotor assembly or stator assemblyrelative to the other of the rotor assembly or stator assembly along thecenterline of the electric machine from the first position to a secondposition at (306) further includes at (310) moving the rotor assemblyrelative to the stator assembly along the centerline of the electricmachine at least 0.5 inches and less than 10 inches. The inclination ofthe air gap allows the rotor assembly or stator assembly to be moved arelatively short distance while still obtaining a desired separationbetween the rotor assembly and stator assembly.

Additionally or alternatively, it should be appreciated that the method300 may be configured to additionally move the rotor assembly or statorassembly along the centerline to one or more a positions between thefirst position and second position, or rather between an engagedposition and a disengaged position. In such manner, the method 300 maybe configured to move the rotor assembly, the stator assembly, or bothin order to affect an efficiency of the electric machine, so as toeffectively control an amount of power extracted by the electric machine(or provided to an engine including the electric machine). In suchmanner, it will be appreciated that the method 300 may further beconfigured to move the rotor assembly, the stator assembly, or bothalong the centerline to control an amount of power extraction from theelectric machine or power provided to an engine including the electricmachine. For example, the method 300 may determine that addition powerextraction is required or desired, and in response may move the rotorassembly, the stator assembly, or both to reduce the air gap andincrease a power extraction. Additionally, or alternatively, the method300 may determine that a lesser amount of power extraction is requiredor desired, and in response may move the rotor assembly, the statorassembly, or both to increase the air gap and reduce a power extraction.Additionally, or alternatively still, the method 300 may determine thataddition power is required or desired to be provided to an engineincluding the electric machine, and in response may move the rotorassembly, the stator assembly, or both to reduce the air gap andincrease a power provided to the engine. Additionally, or alternativelystill, the method 300 may determine that a lesser amount power isrequired or desired to be provided to the engine including the electricmachine, and in response may move the rotor assembly, the statorassembly, or both to increase the air gap and reduce a power provided tothe engine.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

Additional exemplary aspects will be described below with respect to thefollowing clauses:

An electric machine defining a centerline and comprising: a statorassembly; a rotor assembly rotatable relative to the stator assemblyabout the centerline; and an actuator coupled to the rotor assembly, thestator assembly, or both for moving the rotor assembly, the statorassembly, or both along the centerline between a first position and asecond position, the rotor assembly positioned closer to the statorassembly when in the first position than when in the second position.

The electric machine of one or more of these clauses, wherein the firstposition is an engaged position, and wherein the second position is adisengaged position.

The electric machine of one or more of these clauses, wherein the rotorassembly and the stator assembly together define an air gap, and whereinthe air gap defines an angle relative to the centerline greater thanzero degrees and less than 90 degrees.

The electric machine of one or more of these clauses, wherein the angledefined by the air gap relative to the centerline is greater than 10degrees and less than 45 degrees.

The electric machine of one or more of these clauses, wherein the airgap is equal to a first value when the rotor assembly is in the firstposition and is equal to a second value when the rotor assembly is inthe second position, and wherein the second value is at least two timeslarger than the first value and up to 200 times larger than the firstvalue.

The electric machine of one or more of these clauses, wherein theactuator is configured to move the rotor assembly a distance along thecenterline of the electric machine between the first position and thesecond position, wherein the distance is greater than 0.5 inches andless than 10 inches.

The electric machine of one or more of these clauses, wherein thedistance is greater than 1 inch and less than 5 inches.

The electric machine of one or more of these clauses, furthercomprising: a controller operable with the actuator, wherein thecontroller is configured to move the rotor assembly from the firstposition to the second position in response to receiving data indicativeof a fault within the electric machine.

The electric machine of one or more of these clauses, wherein theactuator is further configured to move the rotor assembly along thecenterline to a partial power position located between the firstposition and the second position.

The electric machine of one or more of these clauses, wherein theactuator is coupled to the rotor assembly for moving the rotor assemblyrelative to the stator assembly.

A gas turbine engine defining an engine centerline and comprising: aturbomachine comprising a rotating assembly configured to rotate aboutthe centerline; and an electric machine defining an electric machinecenterline, the electric machine comprising: a stator assembly; a rotorassembly rotatable with the rotating assembly of the turbomachinerelative to the stator assembly about the electric machine centerline;and an actuator coupled to the rotor assembly, the stator assembly, orboth for moving the rotor assembly, the stator assembly, or both alongthe electric machine centerline between a first position and a secondposition, the rotor assembly positioned closer to the stator assemblywhen in the first position than when in the second position.

The gas turbine engine of one or more of these clauses, wherein therotor assembly and stator assembly together define an air gaptherebetween, the air gap defining an angle relative to the electricmachine centerline greater than zero degrees and less than 90 degrees.

The gas turbine engine of one or more of these clauses, wherein theturbomachine comprises a turbine, wherein the rotating assemblycomprises a shaft rotatable with the turbine, wherein the rotor assemblycomprises a connection assembly and a rotor, and wherein the connectionassembly extends between the shaft and the rotor.

The gas turbine engine of one or more of these clauses, wherein theconnection assembly is connected to the shaft through a splinedconnection, and wherein the actuator is coupled to the connectionassembly for moving the connection assembly along the centerlinerelative to the shaft.

The gas turbine engine of one or more of these clauses, wherein theturbomachine further comprises a frame, wherein the stator assembly iscoupled to the frame, and wherein the actuator is also coupled to theframe.

The gas turbine engine of one or more of these clauses, wherein therotating assembly of the turbomachine comprises a plurality of rotorblades, wherein the rotor assembly of the electric machine is coupled tothe plurality of rotor blades at a location outward of the plurality ofrotor blades along a radial direction of the gas turbine engine.

The gas turbine engine of one or more of these clauses, wherein theplurality of rotor blades is a plurality of compressor rotor blades.

A method of operating an electric machine, the electric machinecomprising a stator assembly and a rotor assembly and defining acenterline, the method comprising: operating the electric machine toconvert electrical power to rotational power, to convert rotationalpower to electrical power, or both while the rotor assembly is in afirst position relative to the stator assembly; receiving informationindicative of a fault condition within the electric machine; and movingone of the rotor assembly or stator assembly relative to the other ofthe rotor assembly or stator assembly along the centerline of theelectric machine from the first position to a second position inresponse to receiving information indicative of the fault conditionwithin the electric machine, the rotor assembly positioned closer to thestator assembly in the first position than in the second position.

The method of one or more of these clauses, wherein moving the rotorassembly relative to the stator assembly along the centerline of theelectric machine from the first position to the second positioncomprises moving the rotor assembly relative to the stator assemblyalong the centerline of the electric machine from the first position tothe second position with an actuator coupled to the rotor assembly.

The method of one or more of these clauses, wherein the rotor assemblyand stator assembly together define an air gap therebetween, wherein theair gap defines an angle relative to the centerline greater than zerodegrees and less than 90 degrees, and wherein moving the rotor assemblyrelative to the stator assembly along the centerline of the electricmachine from the first position to a second position comprises movingthe rotor assembly relative to the stator assembly along the centerlineof the electric machine at least 0.5 inches and less than 10 inches.

What is claimed is:
 1. An electric machine defining a centerline andcomprising: a stator assembly defining a first surface; a rotor assemblyrotatable relative to the stator assembly about the centerline anddefining a second surface opposing the first surface, the rotor assemblycomprises a connection assembly and a rotor, the connection assemblyextends between a shaft of a turbomachine and the rotor, the connectionassembly being connected to the shaft through a splined connection, theshaft being rotatable with a turbine of the turbomachine; an air gapformed between the first surface and the second surface that correspondsto a minimum distance between the stator assembly and the rotorassembly; and an actuator coupled to the connection assembly for movingthe connection assembly along the centerline relative to the shaft so asto move the rotor assembly between a first position and a secondposition, wherein the minimum distance is less in the first positionthan in the second position.
 2. The electric machine of claim 1, whereinthe first position is an engaged position, and wherein the secondposition is a disengaged position.
 3. The electric machine of claim 1,wherein the air gap defines an angle relative to the centerline greaterthan zero degrees and less than 90 degrees.
 4. The electric machine ofclaim 3, wherein the angle defined by the air gap relative to thecenterline is greater than 10 degrees and less than 45 degrees.
 5. Theelectric machine of claim 3, wherein the air gap is equal to a firstvalue when the rotor assembly is in the first position and is equal to asecond value when the rotor assembly is in the second position, andwherein the second value is at least two times larger than the firstvalue and up to 200 times larger than the first value.
 6. The electricmachine of claim 3, wherein the actuator is configured to move the rotorassembly a distance along the centerline of the electric machine betweenthe first position and the second position, wherein the distance isgreater than 0.5 inches and less than 10 inches.
 7. The electric machineof claim 6, wherein the distance is greater than 1 inch and less than 5inches.
 8. The electric machine of claim 1, further comprising: acontroller operable with the actuator, wherein the controller isconfigured to move the rotor assembly from the first position to thesecond position in response to receiving data indicative of a faultwithin the electric machine.
 9. The electric machine of claim 1, whereinthe actuator is further configured to move the rotor assembly along thecenterline to a partial power position located between the firstposition and the second position.
 10. The electric machine of claim 1,wherein the actuator is coupled to the rotor assembly for moving therotor assembly relative to the stator assembly.
 11. The electric machineof claim 1, wherein the actuator moves the rotor assembly, the statorassembly, or both along the centerline between the first position andthe second position.
 12. A gas turbine engine defining an enginecenterline and comprising: a turbomachine comprising a turbine and arotating assembly configured to rotate about the centerline, therotating assembly comprises a shaft rotatable with the turbine; and anelectric machine defining an electric machine centerline, the electricmachine comprising a stator assembly defining a first surface; a rotorassembly rotatable with the rotating assembly of the turbomachinerelative to the stator assembly about the electric machine centerlineand defining a second surface opposing the first surface, the rotorassembly also comprises a connection assembly and a rotor, and whereinthe connection assembly extends between the shaft and the rotor; an airgap formed between the first surface and the second surface thatcorresponds to a minimum distance between the stator assembly and therotor assembly; and an actuator coupled to the connection assembly formoving the connection assembly along the electric machine centerlinerelative to the shaft so as to move the rotor assembly between a firstposition and a second position, the connection assembly being connectedto the shaft through a splined connection, and wherein the minimumdistance is less in the first position than in the second position. 13.The gas turbine engine of claim 12, wherein the air gap defines an anglerelative to the electric machine centerline greater than zero degreesand less than 90 degrees.
 14. The gas turbine engine of claim 12,wherein the turbomachine further comprises a frame, wherein the statorassembly is coupled to the frame, and wherein the actuator is alsocoupled to the frame.
 15. The gas turbine engine of claim 12, whereinthe rotating assembly of the turbomachine comprises a plurality of rotorblades, wherein the rotor assembly of the electric machine is coupled tothe plurality of rotor blades at a location outward of the plurality ofrotor blades along a radial direction of the gas turbine engine.
 16. Amethod of operating an electric machine, the electric machinecomprising: a stator assembly defining a first surface, a rotor assemblydefining a second surface opposing the first surface, the rotor assemblycomprises a connection assembly and a rotor, the connection assemblyextends between a shaft of a turbomachine and the rotor, the connectionassembly being connected to the shaft through a splined connection, theshaft being rotatable with a turbine of the turbomachine, and an air gapformed between the first surface and the second surface andcorresponding to a minimum distance between the stator assembly and therotor assembly, the electric machine defining a centerline, the methodcomprising: operating the electric machine to convert electrical powerto rotational power, to convert rotational power to electrical power, orboth while the rotor assembly is in a first position relative to thestator assembly; receiving information indicative of a fault conditionwithin the electric machine; and moving, with an actuator coupled withthe connection assembly, the connection assembly so as to move the rotorassembly relative to the stator assembly along the centerline of theelectric machine from the first position to a second position inresponse to receiving information indicative of the fault conditionwithin the electric machine, wherein the minimum distance is less in thefirst position than in the second position.
 17. The method of claim 16,wherein the air gap defines an angle relative to the centerline greaterthan zero degrees and less than 90 degrees, and wherein moving the rotorassembly relative to the stator assembly along the centerline of theelectric machine from the first position to a second position comprisesmoving the rotor assembly relative to the stator assembly along thecenterline of the electric machine at least 0.5 inches and less than 10inches.